Abstract of Research Plan: Support is requested for the creation of an Ultrafast Processes Laboratory for Biomedical research, as part of the existing Regional Laboratoary Structure at the University of Pennsylvania. The resource will draw on the expertize in laser research and technical back-up capability of the laser laboratory professional and technical staff, and instrumentation. The resource is aimed at meeting the increasing demand in biomedical areas for advanced laser systems. The core projects involve the development of two major instruments: (i) A high speed fluorescence spectrometer designed to obtain high signal/noise fluorescence decays, depolarization evolutions, and spectra on sub-nansosecond timescales with visible or ultraviolet excitation. (ii) A picosecond time-resolved Raman spectrometer capable of recording Raman spectra of species that live for times ranging from a few picoseconds to milliseconds. The instruments meet not only the needs of current research but are sufficiently advanced that they will stimulate new research in the study of intrinsically rapid processes. The core research is the study of fast processes in condensed phases including electronic and vibrational relaxation, electron-transfer, geminate chemical processes, and elucidation of steps in the photodissociation and recombination of diatoms with metalloporphyrins and with hemeproteins. It is suggested that detailed knowledge of vibrational states of intermediates can provide the key to developing realistic structural models for dynamical processes in large molecules. The collaborative user research consists of five projects (i) Time-Resolved Raman Spectra in Reaction Centers (P. L. Dutton) (ii) Time-Resolved Raman of Aromatic Bases in Photodissociating Oxyhemoglobin (W. A. Eaton) (iii) Time-Resolved Resonance Raman in Metalloproteins (Spiro) (iv) Dynamic Structure of Proteins by Fluorescence: Cytochrome-C (J. Vanderkooi) (v) Fluorescence Depolarization and Relaxation in cro-Protein (P. Lee).